(1) Field of the Invention
This invention relates to an improved process for preparation of indoles using N-(.beta.-hydroxy)alkylanilines as their raw materials.
(2) Description of the Prior Art
Indoles have been known as raw materials for the chemical industry and the importance of indole in particular has increased in recent years as raw materials for the syntheses of fragrant substances and amino acids.
A number of attempts have heretofore been made with a view toward synthetically obtaining indoles. However, these attempts were all accompanied by one or more of such problems as multiple step preparation processes being necessary, many by-products being produced, etc.
Among such prior art processes, the preparation process of indoles relying upon gas-phase catalytic reactions of N-(.beta.-hydroxy)alkylanilines needed a further improvement in terms of its selectivity and was accompanied by such problems as severe activity reduction of catalysts due to accumulation of carbonaceous deposits on their surfaces.